I was playing on a server with my friends .
And then i killed a Pigman (Zombified) its sword was dropped and it was 0/32 durability .

I opened a singleplayer and get myself Looting 3 sword and I got:

1 Golden Chestplate 0 Durability

1 Golden Leggings 0 Durability

1 Golden Boots 0 Durability

A lot of Golden Swords 0 Durability

A Crossbow 0 Durability

A Golden Axe 0 Durability

And Finally A Stone Sword 0 Durability

It works with every level of looting but its just luck.